A singulation system for singulation or dicing electronic components, such as semiconductor substrates or packaged semiconductor devices, comprises at least a spindle system and a carrier support such as a chuck table. The axis of the spindle system is orthogonal to the axis of the chuck table and a theta axis table is located on top of the chuck table. The spindle system typically includes either one or two high speed rotating shafts with a sawing blade each. In a dual spindle system, two parallel spindles are arranged either face to face or next to each other.
Dicing may be performed on the semiconductor substrate in one direction by moving the chuck table under a spindle axis while the sawing blade is cutting the semiconductor substrate on a carrier, such as a saw jig, on the theta axis table of the chuck table. The spindle axis may index line by line to complete all the cutting lines required in one direction. Next, the theta table on the chuck table rotates 90 degrees about the theta axis to perform dicing in a direction orthogonal to the first direction. Thus, the semiconductor substrate is singulated into rectangular units.
For increased dicing accuracy, a pattern recognition (PR) camera is mounted on the spindle to recognize alignment marks on the semiconductor substrate before dicing. In this way, accurate dicing can be achieved by determining and adjusting an alignment of the substrate and adjusting its offset in the X-Y-θ axes prior to dicing. There is however a drawback in using a PR camera mounted on the spindle in that the working sequence from substrate loading, PR alignment, dicing to unloading is sequential. This prolongs the cycle time for dicing a substrate. One way to reduce the cycle time is to have a separate vision station for PR alignment. The separate station is located either at one end of a singulation zone for sawing or in between the singulation zone and a loading/unloading zone.
FIG. 1 is a functional block diagram illustrating a conventional bi-directional singulation system 100 with a singulation zone 41 located between a loading/unloading zone 42 and a vision alignment zone 40. A separate vision system 39 for PR alignment is used in this singulation system 100. After a first substrate is loaded onto a saw jig of a first chuck table 37 at the substrate loading/unloading station 12, it moves to the vision alignment zone 40 along a first axis 35 or a second axis 36 for imaging and alignment before proceeding to the dual spindles 34 for dicing. At the same time, a second substrate on a second chuck table 38 may be sawn at the dual spindles 34. A disadvantage of this approach is that the water for cooling the sawing blades and the washed away debris from dicing the second substrate may contaminate the first substrate as it passes through the singulation zone 41.
Another disadvantage of this singulation system 100 is that an additional motion axis is required for moving the vision alignment camera in the separate vision alignment zone 40. This means increased costs and additional space required for incorporating mechanisms to move the vision alignment camera along that axis. Furthermore, cycle time is increased as each semiconductor substrate has to move some distance from the substrate loading/unloading station 12 to the vision alignment zone 40 for positioning before dicing. One prior art document which uses the singulation system described above is US Patent Publication No. US 2002/0184982 A1 entitled “Bidirectional Singulation Saw and Method”.
FIG. 2 is a functional block diagram illustrating a conventional bi-directional singulation system 110 with a vision alignment zone 40 located between a singulation zone 41 and a loading/unloading zone 42. A separate vision system 39 for PR alignment is also used in this system. Unlike the above singulation system, the vision alignment zone 40 is located between the singulation zone 41 and the loading/unloading zone 42. Thus, the substrates do not have to pass through the singulation zone 41 for vision alignment at the vision alignment zone 40. As such, this system has an advantage over the aforesaid conventional singulation system 100 in that the substrates are not contaminated by water and washed away debris in the singulation zone 41. However, this system also exhibits some of the disadvantages of the aforesaid singulation system 100 as an additional motion axis is still required for moving the vision alignment camera in the separate vision alignment zone 40 and the semiconductor substrates are still required to move some distance from the substrate loading/unloading station 12 to the vision alignment zone 40 for positioning before dicing. A prior art example of such a singulation system is found in U.S. Pat. No. 6,826,986 B2 entitled “Bidirectional Singulation System and Method”.
Therefore, it would be desirable to minimise cost and space requirements in singulation systems for electronic components by eliminating the additional motion axis for separately moving the vision alignment system. It would also be desirable to further shorten the cycle time of the process.